Figure 4.

The effects of intracerebroventricular injection of interleukin- (IL-) 1β (50 μg/animal) or Ringer's solution (50 μL) on the mean (± SEM; n = 6 animals per group) concentration of serotonin (5-HT; (a)) and its metabolite 5-hydroxyl-indole-3-acetic acid (5-HIAA; (b)) in the pineal gland collected from control and IL-1β-treated ewes during the short night (SN, May/June) and long night (LN, November/December) photoperiods. Different capital letters indicate significant (P < 0.05) differences according to a two-way ANOVA followed by Tukey's post hoc test.